Straightening shutter or aperture blades

[xwhatsit]

Hello everybody,

Thought I'd give my Rolleicord I a run today. I noticed after I'd finished the whole roll (colour, no less! 😡) that one of the three (!) shutter blades wasn't moving.

It's an old Compur Rapid, goes to 1/300 with the booster spring. I cleaned the clockwork before as it wasn't doing the slow speeds but I never touched the somewhat huckory shutter blades (spot of rust here and there, and a few nicks on some of the leading edges).

It's hanging up because one of the edges has a nick in it and it's actually bent up and stops it from sliding away. I assume there has been a collision or something at the breathtaking 1/300 top speed.

Any tips on flattening shutter blades? I don't think hammering it flat is a good idea, somehow (work hardening etc.). I saw somebody post up how they used scissors to straighten the blades on a Lynx 5000. Anybody have any other advice?

Many thanks,

-Tom

 

[xwhatsit]

Okie dokie. Home now and pulled it apart.

The offending shutter blade was indeed pretty mangled, and upon pulling it apart I see it's managed to shear the riveted pin off too.

I found the site I was thinking of before: http://www.rusted.free.fr/Yashica%20Lynx%205000.html

I tried his technique of the scissors + pressing it tight with some bolts. Seems to have worked pretty well. I'm keen to try his technique of re-riveting the shutter blade with some copper wire, cut down at the tip, then peened over. I even thought I had the right size copper wire to do it, but it's a bit too small unforunately. Might have to wait til tomorrow when I can get a copper pin of suitable diameter.

Has anybody else got any tips on re-riveting shutter or aperture blades? I saw on kyphoto forums somebody soldering a pin on an aperture blade. But he stated (and it makes sense) that it wouldn't be too wise for a shutter blade, because of the significantly higher forces involved.

EDIT: Oh, some photos. Obviously the blade in question is the silver coloured one. I assume it was designed to be differently coloured from the beginning. Note the bent tip, by design; it fits into the milled recess on the shutter housing.

 

[Ranchu]

Well beyond me over here. Just wanted to wish you best luck! Maybe somebody around here has a blade for you...

 

[DaveP]

Lay the blade on something totaly flat like a piece of granite or thick glass, then take a philips screwdriver (since the shaft is round) and push the shaft over it to flatten that turned up edge, like rolling dough. Stick the pivot back in it and use a small center punch, put in the center of the pivot and give it a nice whack to mushroom it. That will hold it in place , then use J B weld on the mushroomed part of the pivot. Thats how I fixed the same problem.

 

[xwhatsit]

The screwdriver trick sounds interesting. The scissors seemed to do a pretty good job, though, so I may just leave it at that in terms of straightening the blade.

So you reckon use the same rivet again? The problem is, the head of the rivet is missing (probably somewhere waiting to fall into the slow speed gear train again 😛). So when I re-insert the rivet, the head of it is flush with the back side of the blade. I don't know that there would be much to mushroom.

JB Weld sounds intriguing though. I've used it on my motorcycles in the past, impressed with how it cured and could be machined. If the centre punch was enough to just spread the end of the pin, maybe it could be bodged with a bit of JB Weld.

 

[DaveP]

That rivet is a problem then, you might measure the pivot and go to your local hobby shop and look thru their selection of brass or steel rod and see if you make another. The other option would be to see if you can find a rivit/pivot from a junk camera.

P.S. Even if the rivit is flush with the blade, it still might be enough for the JB weld to grip.

 

[RichL]

I put it on a hunk of steel and use an orange wood stick to press it back into shape. Like putting down transfer letters if you have ever done that. For tiny rivets I have used brass brads chopped to the length I need.

 

[Murray Kelly]

I once had to replace a rivet in an iris of a Summitar. The repair shop told me to throw it away. I used copper wire, but the forces are a lot less than a shutter blade would experience.
I had to take it to a tech to reassemble because the diaphragm is cone shaped and altho there are 12 leaves the aperture is 6 sided.:bang:

If I did it again (heaven forbid!) I'd use soft iron wire.

Getting the profile low so as to not foul the next leaf is difficult but not impossible.

Good luck!

 

[Sparrow]

Brass stock is surprisingly easy to work with a fine file when spinning in an electric drill, or failing that working jewellers will have small precision centre-lathes that would turn one out in no time.

Solder would be good, but if the blade has been hardened the high carbon "case" will be difficult to tin

 

[xwhatsit]

I have now, in front of me, a tiny brand-new rivet!

I told a co-worker about the rivet, he said his machinist friend likes a challenge... he made a drawing of the rivet (1mm across, 0.7 high etc.). Machinist friend asks "is it in inches? What have I told you about using inches!". Answer -- no -- that's millimetres 😛

I'm told he dropped three of them. Didn't even bother looking for them on the floor amongst the swarf 😛 But finally he managed to hold onto one and here I have it.

It fits perfectly, although as the rivet was torn out of the shutter blade the hole is somewhat elliptical. I think I might need a wee spot of JB Weld after all just to hold onto it where the hole splays out.

Cheers everybody!

 

[RichL]

Wonderful, nice to have friends of friends. "-)

Though I have never tried it on a shutter I would suggest a product called "GOOP SuperMend" it is a two part epoxy similar to JB. In my experience it seems to have just a bit more grab and is a tad less brittle the JB weld.